Modify an existing gradle task

Question

When apply plugin: 'java' in Gradle, it defines among other tasks processResources. I want to substitute the token/parameter in one of the resource file during processResources. I have the following copy task defined in my build.gradle:

import org.apache.tools.ant.filters.ReplaceTokens                                                                                                                                                                                         

task initConfig(type: Copy) {                                                                                                                                                                                                             
    from("src/resources/assets/js") {                                                                                                                                                                                                     
        include 'config.js'                                                                                                                                                                                                               
        filter(ReplaceTokens, tokens: [host: "${System.env.HOST ?: 'localhost:58080'}" as String])                                                                                                                                        
    }                                                                                                                                                                                                                                     
    into "$sourceSets.main.output.resourcesDir/assets/js"                                                                                                                                                                                 
}   

It works fine if I run gradle -q run initConfig. What I want is that this task to be run as part of processResources task, I've tried to put the same logic as following:

processResources << {
    // same code goes here
}

or

processResources {
    doLast {
        // same code goes here
    }
}

None of them works. So, if run gradle -q clean processResources resources are copied, but the token is not replaced.

I don't want to force explicitly run/add initConfig when running the build, so ideally gradle -q build should do everything necessary.

I believe it is possible, as build task itself defines the way to run multiple tasks during its execution. Could not find yet how.

Answer 1

processResources is (a you can view in the docs) a plain task of type Copy. Hence you can configure it exactly in the same way as you're configuring other copy tasks. This will be enough to filter the file:

import org.apache.tools.ant.filters.ReplaceTokens 

apply plugin: 'java'

processResources {
   filter(ReplaceTokens, tokens: ['token.to.replace': 'zombo.com'])
}

Here you can find a simple demo.

Answer 2

ProcessResources is a task provided by java-plugin, you don't need to add << for modifying it's behaviour. Simply try :

processResources{
  //same Code goes here
}

Another workaround could be to add a dependency between processResources and initConfig like this :

processResources{
  dependsOn initConfig
}

This will execute initConfig before processResources.

Hope this help.